Ionic polymer-metal composites (IPMCs) form an important category of electroactive polymers which has both built-in actuation and sensing capabilities. Due to their large bending displacement, low driving voltage, resilience, and biocompatibility, IPMCs have been explored for potential applications in biomimetic robotics, medial devices, and micromanipulators. In most of these applications, compact sensing schemes are desired for feedback control of IPMC actuators to ensure precise and safe operation without using bulky, separate sensors. It is intriguing to utilize the inherent sensory property of an IPMC to achieve simultaneous actuation and sensing, like the self-sensing scheme of piezoelectric materials. However, this approach is difficult to implement due to the very small magnitude of the sensing signal compared to the actuation signal (millivolts versus volts) and the nonlinear, dynamic sensing responses. The idea of using two IPMCs, mechanically coupled in a side-by-side or bilayer configuration, to perform actuation and sensing has been explored. The attempt was reported to be unsuccessful since the sensing signal was buried in the feedthrough coupling signal from actuation.
Therefore, it is desirable to develop an integrated, compact sensing method for electroactive polymers which provides accurate, sensitive measurement of displacement and/or force output and does not appreciably compromise the actuation performance of the actuator with significant added weight or size. The method should provide precise sensory feedback to the actuator, thereby enabling the actuator to deliver exactly the desired displacement or force through closed-loop feedback control.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.